Scallops in curry sauce

• 6 fresh scallops
• 2 oz (50 g) butter

Cut the scallops in thick slices, leaving the coral whole, and set aside. Peel and finely chop the onion. Heat the oil in a saucepan over low heat. Add the onion and fry gently for 5 minutes to soften but not brown. Add the curry powder and cook for 1 minute, stirring occasionally, to draw out the flavour, then stir in the flour. Add the tomato purée and water. Bring to the boil and add the chu